Develop Reference

Questions about capability of Javascript

Many years back, I was told that Javascript was harmful, and I remember being annoyed with endless popup when I right-clicked an image to download it.
Now it seems suddenly that Javascript is great, and you can do a lot of things with it to let users have native-like web application experience.
I admit I have missed 6-7 years of Javascript literature, so I hope to start anew with SO kickstarting me to understand the following:
Is Javascript mainly concerned about user interface i.e. smoothen interaction between application and users and not about logic processing, number crunching or form processing etc.?
Can Javascript write to local hard drive (besides cookies)?
Can Javascript web application run with Javascript capabilities in browsers turned off? (I would think outright no, but an article on Adaptive Path said 'maybe')
Is AJAX illegal to use due to Eolas patent claim? Is it worth it spending effort learning it when the future is not secure? (I know AJAX is not Javascript)
Thanks. Hoping for enlightenment.

Yes. JavaSscript is usually used to enhance the user's experience and make the site easier to use. It is also possible to delegate validation tasks and the like to JavaScript, however (though this should never absolve the server of its responsibility to check input).
No.
That depends on how the application is written. If it's done properly, then the JavaScript will merely enhance the interface, and the application will still work without it; this is called progressive enhancement.
Not at all. AJAX is used extensively on this very site!
One reason for the resurgence of popularity for JavaScript lately is the emergence of several frameworks. These make the process of writing JavaScript much, much easier, allowing tasks that would previously have been horribly complex to be implemented with minimal time and effort. The most popular of these is jQuery, which is a good place to start if you're intending to get in on the action.
Overall, JavaScript is a very powerful tool that allows you to create very rich interfaces. Well worth learning.

Yes, Javascript is all about client side processing, but also about AJAX where it calls back to the server asynchronously so that users do not see pages reloading.
No
No, but there are ways to gracefully degrade the experience for non javascript users. It requires carefult planning however.
No, that lawsuit was just about the browser technology that enables it. As a developer you dont have to worry about that.

Can Javascript write to local hard drive (besides cookies)?
Not really. However, as HTML5 support becomes more widespread you'll be able to use things like Web Storage and Web SQL. You won't be able to write arbitrary files on the user's hard drive, but using those two technologies you'll be able to persistently store and access data.
Can Javascript web application run
with Javascript capabilities in
browsers turned off? (I would think
outright no, but an article on
Adaptive Path said 'maybe')
It really depends on how you define "web application." You can write web apps without using Javascript for anything but UI candy, in which case you can degrade gracefully without without it. However, it's also possible to write web apps that rely heavily (entirely, even) on Javascript, which will utterly fail without it.
Is AJAX illegal to use due to Eolas
patent claim? Is it worth it spending
effort learning it when the future is
not secure?
I'm not a lawyer, but I'd agree with the other answers -- you shouldn't worry about it. I'm certainly still writing AJAX stuff :)
Is Javascript mainly concerned about
user interface i.e. smoothen
interaction between application and
users and not about logic processing,
number crunching or form processing
etc.?
It's about both. And more than that.
Javascript has really come into its own in the past few years. Browsers have gotten a lot faster at executing it quickly, and people have been figuring out new ways to use the language itself to its full potential. You can really start using Javascript like a full-out application programming language, and not just to write little scripts that animate something or validate input.
If you're just getting back into the language and haven't read Crockford yet, I would highly recommend it. It's a great starting point to realizing the full potential of Javascript.
Edit: Some good Crockford Links
Javascript: The World's Most Misunderstood Programming Language
Javascript: The Good Parts (This is a presentation. Crockford also wrote a book by the same name that I haven't read myself, but I hear it's quite excellent.)

It's mainly for UI, but it can be used to save server-time on some operations (for example, Mathoverflow uses it to render LaTeX) and it's becoming popular to do so. But when you do this, you need to be respectful of the end-users time, because JavaScript can hold up some browsers, while it runs. But in general, it's a good and interesting idea.
Not without permission
If it's written correctly, it can. It's called "Graceful degredation" (some other variant terms exist, but the idea is the same). The basic idea is that you have it such that the JavaScript fails 'gracefully', and links that would normally get handled via JavaScript (i.e. to do some inline next-paging) will navigate to a 'backup' page that shows the relevant content.
I don't know about that, but AJAX can be implemented in different ways, XMLHTTPRequest is just one of them :) (And the most common, and suitable). Generally you like a library do this for you anyway (jQuery, or otherwise) but you can do it yourself for fun.

Yes, in my experience JavaScript is generally used to create a streamlined interface and relays information from the client to a server application for processing.
Yes, if the browser is configured to allow this (most aren't by default since this can be very dangerous).
No, JavaScript will not run if the browser is configured to have JavaScript disabled.
I wouldn't forgo learning JavaScript for this reason - as for the legality of the whole thing I wouldn't feel comfortable advising you about this. Still I think JavaScript is worth learning in spite of this situation.

The Eolas patent covers the embedding of objects in a HTML document (see US patent 5,838,906 titled "Distributed hypermedia method for automatically invoking external application providing interaction and display of embedded objects within a hypermedia document") ... this scope would not seem to include AJAX as a suite of technologies (being essentially scripting in a document to load content elements).

Partial answers:
I think all the security vulnerabilities associated with javascript have been fixed? IIRC the problems weren't with javascript, they were with particular browser's implementation of javascript.
I wouldn't worry about any patent claims on the AJAX technology. Patent sueing and counter-sueing is common place in the software world and invariably ends up with the affected parties licencing each other's technology. AJAX is not going anywhere :)

Should I learn Silverlight or JavaScript/JQuery/CSS/HTML?

I'm a seasoned desktop developer working in C++/C#/WinForms/etc. Up until this point, I have done very little in terms of web development. I've come to the point in my career where I feel like I should start doing web development - not to replace my desktop experience but to become more well rounded as a developer.
I already know some HTML and JavaScript, but I am by no means proficient. I'm very comfortable with .NET.
So what is your opinion? Should I focus mastering HTML/CSS/JavaScript/JQuery (with ASP.NET or PHP on the back-end), or should I nurture my .NET experience and dive into Silverlight?
I'm curious about factors such as performance, adoption rate, etc. and any other advice that should guide my decision.
PS: And I have read this article, but it is slightly different from my question.

If you are truly looking to grow your skills as a developer and make the transition into the world of web development. I strongly recommend starting with the HTML, CSS, JavaScript, jQuery, ASP.NET AJAX route.
There are many reasons for this, but more than anything these are the fundamentals of web development. Everything in the end is rendered to the user in HTML, and Javascript/CSS are things that we have to deal with on a regular basis. CSS and cross browser functionality is still and issue and understanding how that works is a fundamental piece to being able to be a proficient developer.
Then the JavaScript/JQuery piece, this is also a now fundamental requirement in many ways as people expect rich, functional User Interfaces and understanding how to leverage these technologies is key.
Sliverlight is great to learn as well, however, I think that the base knowledge and getting experience with general web development techniques is needed first. Especially since silverlight in most cases is just a small portion of a website.

Occasionally you might use Silverlight, ubiquitously you'll use XHTML/JS/CSS. The choice should be self-evident.

Esp. if your primary goal is to become more well rounded as a developer you should IMO first try to get into the fundamental web technologies and only afterwards (if you find a problem that you can't solve with them) combine that with your knowledge about .NET.
While Silverlight and Flash are great tools that help solving certain problems, they shouldn't be your first choice when doing web development.

I'm in the same boat. My feeling is that catching up with a technology thats been going for years is pretty hard. There are developers who will always murder you on Javascript/Ajax etc... So I'd rather be an early adopter of technology. That way you get to be really good at something and get to learn/make mistakes without the pressure of everyone else being so much better than you because they've got a 3yr head start.
As to Silverlight/Flash approaching their expiry dates. I do not agree. 60% of the time spent making RIA apps in Ajax/Html is spent making thing look good (or just making them look like anything at all..). To most developers coming from Winforms or something similar , this is just not a good use of time. Spending time wondering whether your "div" panel is going to appear correctly is so 80's!
IMO, Silverlight is going to be massive for internal business apps. It's just EASIER! Cheaper to build, Cheaper to test and looks better! For a 30 second install on a corporate machine you can have zero-deployment issues and an app that looks like a desktop app in your browser. Why would you use Asp.net? It's also going to be easier to get a designer to skin your app because Silverlight is designed to split design/programming properly.
For the world outside of corporate desktops the adoption will be slower simply because developers are driven by accessibility and getting the most amount of people using their stuff (cos everyones trying to make that cash!). Being compatible with mobile devices would scare most companies away from using Silverlight or Flash so in that space,so I expect Ajax to be the most popular form of web app for a while.
At the moment I'm thinking I'd rather be amazing at a specific area of development than jack of all trades. And it looks like far more fun than spending my life stuck in firebug wondering why my css hasn't taken affect! :-)

Personally I'd go with bolstering your skills with XHTML/CSS/JS/some backend. While Silverlight is gaining speed on the web it's still going to be like Flash -- a small subset of overall web programming. XHTML/etc is everywhere, it's the foundation, and you'll find more use and demand for that.
If you're not looking for "learn something to help me get a job" and rather something to make you a stronger programming I'd highly recommend learning those in combination with PHP. It's going to be a very large difference from what you're used to. Learning completely different things makes you a much stronger programmer.

Ok, this is certainly an opinion question, but here's mine... Any developer today should be well versed in HTML, JavaScript, CSS and SQL.
I just finished a user-group tour where I was part of a panel on development technologies (.NET (me), PHP, Python and Java) and every one of us agreed, you need to know the web "languages" first. Even if you then end up in a silverlight engagement knowing the web languages will help you see how your silverlight stuff fits into the larger picture.
Don't limit yourself, learn the web.

I have a similar background to you and I have decided to concentrate on Silverlight 2 for web development. It really depends on the type of development you want to be doing. Some types of applications are better suited for one versus the other.
I have done a small amount of ASP.NET (with AJAX) and PHP. Personally, I don't like this type of development. Dealing with HTML/CSS issues in various browsers is for the birds. Debugging Silverlight 2 C# versus debugging HTML/CSS/JavaScript is a different world. While there are certainly some great web/AJAX applications out there, I can't help but feel that these are a stop-gap measures. Don't get me wrong, HTML/CSS/JavaScript/AJAX will always have a bigger presence on the net than Silverlight, Flash, etc. But I work on line-of-business applications and making the traditional web model work for these always results in huge UI compromises. I never got into Flash/Flex so Silverlight 2 is the first time I have been able to deliver a browser based application that I can build/debug/support in a similar way to desktop applications.
As for Rich B's comment about needing JavaScript/AJAX skills to use Silverlight, that may have been true for Silverlight 1 but is not true for Silverlight 2. Of course the capability to integrate Silverlight with traditional web development is there, but is not mandatory.

As everybody would say, answer depends on task on hand.
That said, I choose Silverlight 2. I am doing line-of-business apps. Last december, I started doing new app in ASP.NET MVC. Frustrated with wrangling with DIVs, CSS and JS, I did little stealth work over the holidays and reimplemented all already coded functionality of my small app in fraction in time.
It did help that I was already familiar with XAML (from WPF app I was doing earlier), but main winning point with my boss was speed and ease of development. Suddenly, I was not spending time tweaking my presentation layer, but coding business rules instead.
So far, everything looks great. My coding is chugging at steady pace, my job satisfaction is higher, I enjoy coding again :)
Point is, for LOBs, in controlled environment, Silverlight 2 wins hands down. I am not familiar with Flex, but I hear it is quite similar to SL2 in dev workflow kind of way.

I tend to believe that Silverlight/Flash development should be left to real designers... people who have not only a nack for graphic design but also have a solid understanding the flow of animation. When you work with web technologies (HTML and CSS particularly) you can work very well off of a designers comps in creating a beautiful web interface and working from that framework to make it come alive with Javascript/Jquery.
More importantly, the breadth and scope of web applications is so wide as to tackle a huge variety of concerns, where the applications of Silverlight and Flash are much more limited. While you do have a strong advantage jumping straight into Silverlight with your existing skill set, the installed base of Silverlight is light enough that you won't be able to easily have your work viewed by everybody.
Also, (coming from a ASP.NET MVC programmer) you have plenty of opportunity to nurture your .Net skills in an ASP.Net realm. What I love most about the MVC strategy is that I have full control over my HTML again (a plus for maintaining look and feel) and have a full range of tooling to allow me to build insanely complex data driven sites in a fraction of the time that it used to take me. The only difference between web development and winforms development is the medium that you use to interact with the user.

Microsoft's annual MIX conference starts on March 18th. This conference is focused on Microsoft's web technologies. Historically, the sessions have been posted online within 72 hours (http://visitmix.com/).
Considering we are so close to March 18th, I would recommend waiting to see what gets announced. There may be something there that gets you excited in regards to one technology or another. I think it will be more beneficial for you to find something you are excited about. This will make the learning process more enjoyable.
Chad Campbell
Author of Silverlight 2 in Action

I think that Silverlight (and Flash) are rapidly approaching their expiry dates. As JavaScript gets faster as JIT compilers start showing up (like in Chrome, Firefox 3.1 and Safari 4), and as HTML support gets better (HTML5), the need for plugins to display fancy rendered widgets will diminish. I am, even today, amazed at what is possible using HTML+CSS+JS, things I never would have imagined possible without something like Silverlight.

My cousin is a web designer/developer and he told me many people want you to know the action script behind flash, not only the design part. So on the flip side, to make the most of flash you need to be a decent programmer. Flash is basically a combination of design and programming....so obviously you have to be able to do both if you're going to master the program. A good designer can make it look pretty and that's it. You have to program in order to give it functionality.
Unless there is some magic flash action script writer that I have no idea about. =/

Should you design websites that require JavaScript in this day & age?

It's fall of 2008, and I still hear developers say that you should not design a site that requires JavaScript.
I understand that you should develop sites that degrade gracefully when JS is not present/on. But at what point do you not include funcitonality that can only be powered by JS?
I guess the question comes down to demographics. Are there numbers out there of how many folks are browsing without JS?

Just as long as you're aware of the accessibility limitations you might be introducing, ie for users of screen-reading software, etc.
It's one thing to exclude people because they choose to turn off JS or use a browser which doesn't support it, it's entirely another to exclude them because of a disability.

Two simple questions to help you decide...
Does using javascript provide some
core functionality of your site?
Are you prepared to limit your
potential users to those who have
JS? (ie. Most people)
If you answer yes to both of those, go for it!
Websites are moving (have moved?) from static pages of information to interactive web applications. Without something like Javascript or Flash, making compelling user interactions is sometimes not possible.

Designing to degrade gracefully is the most that should be done. We are moving/have moved past the point of simple web "sites" to web "applications". The only option besides client side scripting to add round trips to the server.
I think (personal opinion) that the "don't use JavaScript" comes more from a lack of understanding of what JavaScript is/does than any actual market data that shows a significant number of people are browsing without it.

It's reasonable to design sites that use JavaScript but it is not safe to assume that all clients have support for Javascript and therefore it is important that you provide a satisfactory experience even when JavaScript is not available

Search Engines don't support JavaScript. They're also blind and don't support CSS. So my suggestion to you is to make sure that the part of your product that needs to be indexable by search engines works without JavaScript and CSS. After that, it really depends on the needs of your users.
If you have a very limited subset of users, then you can actually query them. But to remember that 10% of the population has some form of impairment ranging from vision issues (low vision, color-blindness, etc.) or motor functions (low hand dexterity). These problems tend to be more prominent in the elderly and the knowingly disabled
If your site will target the general audience of Internet users then please make it degrade gracefully, but if you can't do that, then make a no-JavaScript version (like G-mail has).

I think the days of "content sites only" are gone. What we see now is WWW emerging as the platform of web applications, and the latest developments in the browser front (speeding up JS in particular) ar indication of this.
There can be no yes/no answer to your question - you should decide, where on content site<---->web application continuum your site is and how essential is the experience provided by JavaScript. In my opinion - yes it is acceptable to have web applications which require Javascript to function.

Degrading gracefully is a must. At a minimum, you sure make use of the NOSCRIPT tag in order to inform potential customers first that your site requires javascript, and secondly why you require it.
If it's for flashy menus and presentations that I could honestly care less about then I probably won't bother coming back. If there's a real reason that you're requiring javascript (client-side validation on forms, or a real situation that requires AJAX for performance reasons) then say so and your visitors will respond accordingly.
I install extensions that limit both Javascript and Cookies. Websites that don't prominently state their requirements of both usually don't get a second visit unless there's a real need for it.

You should never design a public site to rely on ANY technology/platform. The user agent may not display colour (think screen readers), display graphics (again, think screen readers or text only browsers such as links), etc.
Design your site for the lowest common denominator and then progressively enhance it to add support for specific technologies.
To answer the question directly: No, you cannot assume your users have Javascript, so your site should work without it. Once it does, enhance it with Javascript.

it's not about browser capability, it's about user control. People who install the noscript plugin for firefox so they don't have to put up with punch-the-monkey garbage ( the same problem that inspired stack overflow) will not allow your web site to do anything non-static until they trust you.

In terms of client software consider users/customers who are using a browser that supports some but not all Javascript. For example, most mobile phone browsers support a bit of Javascript but nothing very complicated. The browsers on devices such as the Playstation 3 are similar.
Then there are browsers such as Opera Mini, which support a lot of Javascript but are operating in an environment where the scripts are running on a server that then sends the results to a mobile device.

You should design websites with Javascript in mind--but not implemented. Consider, build it where every click, every action, performs a round trip to the server. That's the default functionality for older browsers, and those without JS turned on.
Then, after it's all built, and everything is working properly, add in JavaScript which hijacks the link, button and other events, and overlay their standard functionality with the Javascript functionality you're wanting.
Building the application like this means that it will ALWAYS work, which ultimately is what you're wanting.

The received wisdom answer is that you can use JavaScript (or any other technology) providing that it 'degrades gracefully'...
I have experience with disability organisations, so accessibility is important to me. But equally, I'm in the business of building attractive, usable websites, so javascript can be a powerful ally. It's a difficult call, but if you can build a rich, javascript-aided site, without completely alienating non-js vistors, then do so. If not, you will have to look at the context of the site and decide which way to jump.
Regardless, there are no rights and wrongs with this question. However, in some countries, there is a requirement to build 'public' sites to be accessible, so this may be yet another factor in your decision. [In the UK, it is the Disability Discrimination Act.. though to my knowledge, no company has been prosecuted for failure to comply]

JavaScript is great for extending the browser to do things like google maps. But it's a pointy instrument, so use it with care.
My bank web site uses JavaScript for basic navigation between pages. Sigh. As a result, it's not usable from my mobile device.
Make sure you're familiar with the Rule of Least Power when considering JavaScript:
When designing computer systems, one
is often faced with a choice between
using a more or less powerful language
for publishing information, for
expressing constraints, or for solving
some problem. This finding explores
tradeoffs relating the choice of
language to reusability of
information. The "Rule of Least Power"
suggests choosing the least powerful
language suitable for a given purpose.

5% according to these statistics: http://www.w3schools.com/browsers/browsers_stats.asp

As you said, demographics. The web is expanding onto devices that doesn't have very much power, for instance cellphones. If your site is usable without javascript, Opera Mini will likely show your site without any problems.

I think Javascript implementations in most modern browsers have now reached a reasonable level of maturity and there are a bunch of Javascript UI frameworks which let you build very attractive Javascript based web applications using web-services and such (regardless of the back-end server platform).
An example is ExtJS - they have got a very extensive AJAX + UI widget framework which I recently used to build a full fledged internal web-app for a client with an ASP.NET backend (for webservices).

I think it comes down to what you're about to do. Are you writing a web APPLICATION? Then I think you're bound to use javascript and/or something like GWT. Just have a look at all the social sites, and google aplications like gmail. If you're writing a webpage with product descriptions and hardly any interactivity, then you can make the javascript optional.

I agree with the majority of the stackoverflow respondents. JavaScript has matured and offers an "extra" level of functionality to a webpage, especially for forms. Those who turn off cookies and JS have likely been bitten while surfing in dangerous waters. For the corporate power users that pay my way either in B2B or retail sites, JS is a proven and trusty tool. Until something better comes along (and it will) I'm sticking with JS.

There's addon for Firefox called NoScript which have 27,501,701 downloads. If you site won't work without JavaScript most of those guys wouldn't want to use it.
Why you would install that addon? Ever wanted to get rid of the popup on the site that cover the most of the useful text you want to rid? Or disable flash animation? Or be sure that evil site won't steal your cookies?

Some corporate environments won't allow Javascript, by policy or by firewall. It closes the door to one avenue of virus infection.
Whether you think this is a good idea or not, realize that not everyone has full control over their browser and it might not be their choice.

There is a gradient between web sites and web applications. However, you should alway be able to say "we are building a web site" or "we are building a web application".
Web sites should be readable down to plain HTML (no CSS, no images, no JavaScript).
Web applications, of course, could just say "Sorry, JavaScript is needed" (which also assumes CSS for layout). Application should still be able to work without images.

The accessibility issue is the only important technical issue, all other issues can be socially engineered. When one says that javascript reduced accessibility and another says that Web Applications can use javascript, can we take these two together to imply that all blind people are unemployed? There has to be some kind of momentum in making javascript accessible. Maybe a Screenreader object on the javascript side which can detect the presence of a screenreader and then maybe send hints to the screenreader, Screenreaders which can hook onto the browser, and maybe it gets glued together with a screenreader toolbar.

if you want your site viewable by the top 100 companies in the US. I would write without javascript.

Independence from Javascript and graceful degradation are important to an application despite the actual demographics -- because such an application probably has better software design.
The "human user without Javascript" may be purely hypothetical (for example, if you're trying to make money with your product). But designing for that hypothetical user encourages modular software design which will pay off as you continue to develop your app.
Javascript provides functionality. HTML provides data (on the page itself, and via links that point to more data). As a general rule that reaches well beyond browser apps: A well-designed software product will separate data from functionality. All data should be available, and the functionality should be a separate layer that consumes the data.
If your Javascript is creating data at runtime, then it's time to get specific and figure out whether your webpage really is a piece of software (e.g. a mortgage calculator) or whether it's a document containing data (e.g. a list of mortgage interest rates). This should tell you whether it makes sense to rely on Javascript.
As a final note/example, demographics can be misleading. Relatively few humans browse your site without Javascript, but lots of machines (search bots, data miners, screen readers for the disabled, etc.) are browsing your site without Javascript. Again, the distinction between data and functionality are important -- the bots are just making requests and looking for data in the responses. They don't need functionality. But if your user needs to invoke functions just to make your data accessible, the bots are getting no value from your site.
One side point about the screen readers and other accessibility considerations for the disabled. This is an important niche demographic: a mind that navigates data in a human way, but who can only get data from your site in the same way machines get it. By providing data cleanly and semantically on your page, you make it available to the largest possible set of accessibility tools.
Note this doesn't exclude Javascript from consideration. Our mortgage calculator example can still work: accept input from the user, invoke Javascript, and write the output back into the clean semantic data layer of the page. Screen readers can then read it! And if they can't, you're encouraging the development of better screen readers that can.

If you expect your app to work for everyone, you'll need a backup for all your javascript functionality. If it's form validation, you should also check the data on the server before saving it. So the answer is Yes, it's okay, but have a backup. Do not rely on it.

As many people are saying, it's important to consider your user base, but whoever your users are there's a strong possibility that some (stats say 10%) of them will have some sort of disabilities, and screen readers don't like javascript. If you're only adding simple things, a javascript menu or something, then just make it degrade (or don't do it). If the site depends on javascript to work properly, make two versions, one for javascript and one without.
I generally find that anything too javascript heavy is very difficult to make degrade well without just having javascript re-writing the page to a javascript version if the user can take it. Given this, it's well worth writing two pages from square one for complicated stuff.
I would say that there are very very very few web sites that should be running without some support for users without javascript. You'd need to have a very dynamic application that completely didn't make sense as static pages,or you'd need to have a audience you could guarantee were ok with it (like on an office Intranet say).

Well, it depends on your userbase. If you know that people will be using your site from mobile devices, it's good to have unobtrusive JavaScript. However, if you're trying to appeal to a tech-savvy crowd, don't bother with it.
However, if you're appealing to a crowd that may be using screen readers (blind people), I'd highly suggest using WAI-ARIA standards. Dojo's widget system has full support for this, and would be a great and easy way to do it.
Anyway, in most cases, you don't need unobtrusive JavaScript. Most people who have JavaScript disabled are either using a smartphone, using Lynx, or have NoScript installed. It's enabled by default in all the major browsers, so you shouldn't have to worry.
Lastly, it's good to at least have some unobtrusive JavaScript. <noscript> tags are your best friend. For example, one may want to replace a widget that draws rating stars with text. Example using dojo:
<div dojoType="dojox.Rating" stars="5" value="4"></div>
<noscript>4/5</noscript>

It's the 21st century. People not permitting JavaScript need to exit the last millennium, posthaste. It's a mature, widely used, and very useful technology that is one of the foundations of the recent expansion in useful web services.

You should be tying the functionality of your website to your audience. That being said, every modern browser (save for the mobile platform) includes javascript, and so unless your audience includes luddites with decade old computers, you can assume they have javascript.
The people you need to worry about, then, are those that specifically turn it off. This includes:
Corporate networks with tough security (not common, but some financial and defense institutions)
Paranoid web-heads
So, first, who is your audience? Are there other websites that are comparable to your target? Look at their site and success - do they degrade gracefully, and would yo be satisfied with their level of success?
If you are targeting mobile applications, though, you can't guarantee javascript.
-Adam

I would say that you should look at your target audience. If you can reasonably expect that they will have js enabled, and making everything work without any js is too much of a pain, then by all means - go ahead and ignore the non-js crowd, if, on the other hand you have to create a site that will be used by a very large audience/or you are perhaps building a government web site, then you must make sure that everything works, and it is easier in those cases to first build the site so that it works without any js, and add all the nice time-saving ajaxy bits later.
In general though, almost everyone has js enabled by default.
Though you should be aware that server-side validation of user posted data is a must in either case.

Will server-side JavaScript take off? Which implementation is most stable? [closed]

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Closed 10 years ago.
Does anyone see server-side JavaScript taking off? There are a couple of implementations out there, but it all seems to be a bit of a stretch (as in, "doing it BECAUSE WE CAN" type of attitude).
I'm curious to know if anyone actually writes JavaScript for the server-side and what their experiences with it have been to date.
Also, which implementation is generally seen as the most stable?

I like to read Googler Steve Yegge's blog, and recently I came across this article of his where he argues that Mozilla Rhino is a good solution for server-side JS. It's a somewhat sloppy transcript, you might prefer to watch the video of the talk. It also offers a little bit of insight on why he thinks server-side JS is a good idea in the first place (or rather, why he thinks that it's a good idea to use a dynamic language to script Java). I thought the points he makes were convincing, so you might want to check it out.
A while earlier, he also posted something about dynamic languages in general (he's a big fan of them), just in case you were wondering why to use JS at all.

Why would you want to process
something in Javascript when you can
process it in PHP or ASP.NET which are
designed specifically for this task?
Perhaps because JavaScript is a more powerful programming language than those two? For example, it has functions as first-class data types and support for closures.
Steve Yegge has blogged about porting Ruby on Rails to server-side JavaScript as an internal project within Google ("Rhino on Rails"). He did it because he likes Rails but using Ruby isn't allowed within Google.

Before it was acquired by Google, JotSpot used server-side JavaScript to let you query their database and display your pages. They used Rhino to do it. CouchDB uses server-side JavaScript to create views of their database.
As you can see from these examples, a great way to use JavaScript on the server is for plugins. One of the reasons it's used is that you can create a very isolated sandbox for people to run their code in. Also, because of the way that JavaScript as a language works, you can provide a user tooling specifically honed to the tasks your users need to complete. If you do this right, users don't need to learn a new language to complete their tasks, a quick glance at your API and examples is enough to get them on their way. Compare this to many of the other languages and you can see why using server-side JavaScript to provide a plugin architecture is so enticing.
A secondary popular solution, one which can be seen through a project like Jaxer, is that a common problem of web applications that do client-side validation is that, since JavaScript is easily bypassed in the browser, validation has to be run once again on the server. A system like Jaxer allows you to write some validation functionality that is reusable between both server and client.

Support for JS on the server has been getting stronger and the number of frameworks is getting bigger even faster.
Just recently the serversideJS group was founded. They have a lot of smart people that have been working on serverside JS for years (some of them more then 10).
The goal for this project is to create
a standard library that will
ultimately allow web developers to
choose among any number of web
frameworks and tools and run that code
on the platform that makes the most
sense for their application.
to the people who say "why would you choose JS over java or any other language?" - you should read this Re-Introduction by Crockford and forget about the DOM - the DOM is superugly, but that's not JS fault and JS is not the DOM.

I've never even heard of this, but it strikes me as using the wrong tool for the job. Since programming languages are just tools designed to help us solve some problem.
Why would you want to process something in Javascript when you can process it in PHP or ASP.NET which are designed specifically for this task?
Sure you can pound a nail in with a screw driver, but a hammer works much better because it was actually designed for it...
So no, I don't see it taking off.

Well, plain ol' ASP supported JavaScript server-side years ago and everyone onad their dog used VBShiate instead. But I have to agree with the others: JS does not seem to be the right tool here - and I love to do client-side JS :)

I personally did a whole site in server side JavaScript using ASP. I found it quite enjoyable because I was able to have some good code reuse. This included:
validation of parameters
object modeling
object transport
Coupled with a higher-level modeling tool and code gen, I had fun with that project.
I have no numbers on perf unfortunately, since it is used only on an intranet. However, I have to assume performance is on par with VBScript backed ASP sites.

It seems like most of you are put off by this idea because of how unpleasant the various client-side implementations of Javascript have been. I would check out existing solutions before passing judgment, though, because remember that no particular SS/JS solution is tied to the JS implementations currently being used in browsers. Javascript is based on ECMAScript, remember, a spec that is currently in a fairly mature state. I suspect that a SS/JS solution that supports more recent ECMA specs would be no more cumbersome than using other scripting languages for the task. Remember, Ruby wasn't written to be a "web language" originally, either.

Does anyone see Server-side Javascript
taking off?
Try looking at http://www.appjet.com a startup doing hosted JavaScript applications to get a feel for what you can do. I especially like the learning process which gently nudges the user to build things with a minimal overhead ~ http://appjet.com/learn-to-program/lessons/intro
Now it might seem a weird idea at the moment to use JavaScript but think back when PC's started coming out. Every nerd I knew of was typing away at their new Trash-80's, Commodore64's, Apple ]['s typing in games or simple apps in BASIC.
Where is todays basic for the younger hacker?
It is just possible that JavaScript could do for Web based server side apps as BASIC did for the PC.

XChat can run Javascript plugins.
I've some accounting software completely written in Javascript.
There's this interesting IO library for V8: http://tinyclouds.org/node/
CouchDB is a document database with 'queries' written in Javascript (TraceMonkey).
Considering this, i believe, server-side Javascript did take off.

Server-side programming has been around for a lot longer than client side, and has lots of good solutions already.
JavaScript has survived and become popular purely because developers have very little choice in the matter - it's the only language that can interact with a DOM. Its only competition on the client side is from things like Flash and Silverlight which have a very different model.
This is also why JavaScript has received so much effort to smart it up and add modern features. If it were possible for the whole browser market to drop JavaScript and replace it with something designed properly for the task, I'm sure they would. As it stands Javascript has strange prototype-based objects, a few neat functional programming features, limited and quirky collections and very few libraries.
For small scripts it's fine, but it's a horrible language for writing large complicated systems. That things like Firefox and Gmail are (partly) written in it is a heroic accomplishment on their part, not a sign that the language is ready for real application development.

Flash Media Server is scripted by using Server Side Action Script, which is really just javascript (ECMAScript). So, I do it a lot. In fact, most of my day was dealing with SSAS.
And I hate it. Though to be fair, a bunch of that is more related to the (not so great) codebase I inherited than the actual language.

I think server-side Javascript is guarenteed to take off. Its only a matter of time.
Mozilla, Google, and Adobe have so much vested interest for Javascript that it would take a miracle to dislodge it from the browser world. The next logical step is to move this into the server-side.
This is a step towards moving away from the hodge podge of Internet technology that usually includes all of these
HTML
CSS
Javascript
Serverside Language J2EE/ASP/Ruby/Python/PHP
SQL
I haven't heard much about the current state of Javascript Server frameworks, except that they are mostly incomplete.

I see server-side js will offer considerable advantages in future applications. Why? Web apps that can go offline, client-side db store, google gears, etc...
Following this trend, more and more logic are moving into the client-side. Use an ORM that works for client-side, and use another on server-side (be it PHP / Ruby / whatever), write your synchronization logic twice in two different languages, write your business logic twice in two different languages?
How about use js on the client AND the server side and write the code once?
Convincing?

Personaly i've been developing and using my own JavaScript framework for about 4 years
now.
The good thing about JS on serverside is that implemented in ASP Classic you don't need
any other plugin or software installed, besides i'm also using my javascript (client)
framework on my server, that allows me to enjoy of the same functionality and proven
performance of my functions at both environments client and serverside.
Not only for data validation, but also lets say HTML or CSS dynamic constructions
can be done client or serverside, at least with my framework.
So far it works fast, i have nothing to complain or regret except its great usability
and scalability that i have been enjoying during this past 4 years, until the point
that i'm changing my ASP Classic code to javascript code.
You can see it in pratice at http://www.laferia.com.do

Node.js has taken off and proven that server-side JavaScript is here to stay =)

I can't see most developers getting over their distaste for client-side JavaScript programming. I'd rather go to Java for server-side stuff before choosing JavaScript.

Building Standalone Applications in JavaScript

With the increased power of JavaScript frameworks like YUI, JQuery, and Prototype, and debugging tools like Firebug, doing an application entirely in browser-side JavaScript looks like a great way to make simple applications like puzzle games and specialized calculators.
Is there any downside to this other than exposing your source code? How should you handle data storage for this kind of program?
Edit: yes, Gears and cookies can be used for local storage, but you can't easily get access to files and other objects the user already has around. You also can't save data to a file for a user without having them invoke some browser feature like printing to PDF or saving page as a file.

I've written several application in JS including a spreadsheet.
Upside:
great language
short code-run-review cycle
DOM manipulation is great for UI design
clients on every computer (and phone)
Downside:
differences between browsers (especially IE)
code base scalability (with no intrinsic support for namespaces and classes)
no good debuggers (especially, again, for IE)
performance (even though great progress has been made with FireFox and Safari)
You need to write some server code as well.
Bottom line: Go for it. I did.

Another option for developing simple desktop like applications or games in JavaScript is Adobe AIR. You can build your app code in either HTML + JavaScript or using Flash/Flex or a combination of both. It has the advantage of being cross-platform (actually cross-platform, Linux, OS X, and Windows. Not just Windows and OS X).
Heck, it may be the only time in your career as a developer that you can write a web page and ONLY target ONE browser.

SproutCore is a wholly JavaScript-hosted application framework, borrowing concepts particularly from Cocoa (such as KVO) and Ruby on Rails (such as using a CLI generator for your models, views and controllers). It includes Prototype, but builds plenty of stuff such as sophisticated controls on top of that. Its Photos demo is arguably impressive (especially in Safari 3.1).
Greg already pointed you to Gears; in addition, HTML 5 will come with a standardized means of local storage. Safari 3.1 ships with an implementation where you have a per-site SQLite database with user-settable size maximums, as well as a built-in database browser with SQL querying. Unfortunately, it will be a long time until we can expect broad browser support. Until then, Gears is indeed an alternative (but not for Safari… yet!). For simpler storage, there is of course always cookies.

The downside to this would be that you are at the mercy of them having js enabled. I'm not sure that this is a big deal now. Virtually every browser supports js and has it enabled by default.
Of course the other downside would be performance. You are again at the mercy of the client handling all the intensive work. This also may not be that big of a deal, and would be dependent on the type of app you are building.
I've never used Gears, but it looks like it is worth a shot. The backup plan would be to run some server side script through ajax that dumps your data somewhere.
Not completely client side, but oh well.

Nihilogic (not my site) does a lot of stuff with Javascript. They even have several games that they've made in Javascript.
I've also seen a neat roguelike game made in Javascript. Unfortunately, I can't remember what it was called...

If you want to write a standalone JavaScript application, look at XULrunner. It's what Firefox is built on, but it is also built so that you can distribute it as an application runtime. You will write some of the interface in JavaScript and use JavaScript for your code.

Gears might provide the client-side persistent data storage you need. There isn't a terribly good way of not exposing your source code, though. You could obfuscate it but that only helps somewhat.
I've done simple apps like this for stuff like a Sudoku solver.

You might run into performance issues given that you're completely at the mercy of the client's Javascript interpreter. Gears would be a nice way of data storage, but I don't think it has penetrated the market that much. You could just use cookies if you're not fussy about that kind of thing.

I'm with ScottKoon here, Adobe AIR is great. I've really only made one really nice (imho) widget thus far, but I did so using jQuery and Prototype.js, which floored in such wonderful ways because I didn't have to learn a whole new event model. Adobe AIR is really sweet, the memory foot print isn't too bad, upgrading to a new version is built into AIR so it's almost automatic, and best of all it's cross-platform...they even have an alpha-version for Linux, but it works pretty well already on my Eee.

Standalone games in GWT:
http://gpokr.com/
http://kdice.com/

In regard to saving files from a javascript application:
I am really excited about the possibilities of client-side applications. Flash 10 introduced the ability to create files for save right in the browser. I thought it was super cool, so I built a javascript+flash component to wrap the saving feature. Right now it only works for creating text based files (vcard, ical, xml, html, css, etc.)
Downloadify Home Page
Source Code & Documentation on Github
See It In Use at Starter for jQuery
I am looking to add support for non-text files soon, but this is a start.

My RSS feeds have served me well- I found that Javascript roguelike!
It's called The Tombs of Asciiroth.

Given that you're going to be writing some server code anyway, it makes sense to keep storage on the server for a lot of domains (address books, poker scores, gui configuration, etc.,.) For anything the size of what you'll get in Webkit or Gears, you can probably also keep it on your server.
The advantage of keeping it on your server is two-fold:
You can integrate it fairly simply as a Model layer in a typical MVC framework, and,
Users get a consistent view without being tied to their browser/PC, or in a less-than-ideal environment (Internet Cafés).
The server code for handling this can also be fairly trivial, particularly if it's written with this task in mind, so it's not a huge cognitive burden.

Go with qooxdoo. They recently realsed 1.0, although most users of it say it was ripe for 1.0 at least two versions ago.
I compared qooxdoo with YUI and ext, and I think qooxdoo is the way to go for programmers - YUI isn't that polished as qooxdoo, from a programmer's point of view and ext has a not so friendly licensing model.
A few of the strong points (for me) of qooxdoo are:
extremely clean code
the nicest OO programming model I've seen among Javascript frameworks
an extremely rich UI widget library
It also features a test runner for unit tests, an API doc generator and reader, a logging facility, and several useful features for debugging, grouped under something called Inspector.
The only downside is that there aren't readymade themes (something like skins) for qooxdoo. But creating your own theme is quite easy.